Quantitative hemodynamic assessment of the flow through cardiovascular valves is a matter of fundamental importance in many clinical practical aspects for diagnosis and choice of optimal therapeutic options (1-4). A relevant example is represented by the flow that regurgitates through the mitral valve when this does not close correctly; the correct evaluation of such a regurgitant flow gives a functional measure of the actual valvular disease.
Information about the point-wise velocity in the blood are obtained by echographs that support measurements of the Doppler type, however the Doppler data acquired by echographic machines do not give explicitly, in general, values about the flow that passes through a valve and these data require a further analysis to produce an estimate of this important quantity.
Several investigators have tried to quantify the regurgitant volume and the effective regurgitant orifice using the proximal iso-velocity surface area (PISA) concept by color flow mapping and the principle of flow continuity (5-7). The PISA method is based on the assumption that the iso-velocity contours are hemispherical proximal to the regurgitant orifice. However, this assumption is severely hampered by the complex flow fields that are present in the heart (8). In addition, the two-dimensional color Doppler, while able to provide detailed information regarding the instantaneous velocity of flow parallel to the Doppler scan direction, is unable to represent the orthogonal components of flow velocities. Obviously, such an approach is inherently inaccurate for the estimation of the regurgitant volume.
We propose he a new method that, on the basis of the color Doppler data produced by echographic machines, is able to accurately quantify the valvular flow. The objective is to take an instantaneous two-dimensional color flow image of a valvular flow (mitral regurgitation) and evaluate the corresponding instantaneous discharge that passes through the valve.